A problem which is solved by this invention relates to correcting a form of electron beam deflection distortion which is encountered during the high magnification operation of a scanning charge particle microprobe, such as in a scanning electron microscope. It is theorized that this distortion may be caused by the inherent change in electrical or magnetic fields which are utilized to cause the required deflection of the microprobe for "stereo" operation during the scanning of the beam over a specimen under examination. Because of the sensitivity of this small electron probe to the effects of changing fields, small electrostatic or magnetic fields produce identifiable deflection of the probe. I have discovered that due to the inherent nature of a changing magnetic field inducing an eddy current in any electrical conductor through which the field passes, an inherent distortion is introduced into the microprobes deflection system as during the deflection of the beam for different incident angle viewing.
The very existence of the eddy current which has been unintentionally induced in the conductors making up the deflection system in turn causes a magnetic field in the general system which opposes the change of the original field. If, therefore, the initial field which is applied to the electron beam is sufficient to cause the previously calculated desired deflection, the opposition to that field generated by the above described unwanted currents induced within the field will cause the previously calculated field to be insufficient for the original deflection desired. Thus, it becomes apparent that inherent within the microscope system is a somewhat insidious field generator which tends to defeat a part of the original objective of the total system.